Home Grown is an educational,
entertaining, question-answer column seen weekly in "News from
the Genesee MSUE Office," a weekly newsletter for Genesee
County Master Gardeners. Special thanks to the Genesee, Oakland and
Livingston county MSU Extension offices for providing this service.

HOME GROWN 305

My big maples in front of my house are loosing leaves. There are perfect, green, healthy leaves lying on the ground. I donít want my trees to die. Iíve been picking up leaves and burning them immediately. It hasnít helped. How do I stop this?

You wait. Itís cheap and doesnít involve any effort or chemicals. This too, shall pass with no damage to the trees. But Iím worried about you. If you examine the leaf, you will notice that the ďstemĒ of the leaf that connects it to the twig is darkened and appears pinched off. The stemmy thing is called a petiole. This damage is the work of the Maple Petiole Borer. How clever; itís name is what it does. This tiny insect is a sawfly. In May, mommy petiole borer lands on the leaves, right at the base of the petiole, close to the leaf. She lays her eggs and flaps off into oblivion. The kiddies hatch and begin to eat the middle out of the petiole. It takes about a month for the kiddies to complete their mission. Then, the leaf breaks off and floats to earth where you find it, with much concern and dismay. The larva remains up in the tree in the petiole stub that broke off. Eventually, the larvae will drop to the ground and pupate just below the soil level. The tree has thousands of leaves and the small number that is lost will not affect its health. The trees are currently producing new twigs and leaves and will more than replace the lost ones. The trees are safe to shade your house another day. Letís look at what wonít work, now that you know who is responsible. Picking up leaves and destroying them wonít get the larvae. They are still in the tree. Nuking the tree with insecticides will not get mommy because sheís there and gone without ever ringing your doorbell. The kids are in the petiole stub and protected. Pouring chemicals on the ground is not going to kill the children that are pupating. The pesticide stuff is going to kill plenty of innocent bystanders of the insect world and put you in contact with insecticides for no particular reason. If you must worry about something, concentrate your worries on something that you might affect like the price of gas or the fate of the National Hockey League.

I have an in-ground irrigation system for my lawn and the grass looks pretty good, considering the heat and drought. But my trees and shrubs look bad. Are they getting too much water? The system runs every day.

Quite the contrary, Holmes, the drought game is still afoot. The trees and shrubs are not getting enough water to maintain them during this kind of weather. In the Wide World of Plants, what grass needs and what other plants need are very different. Grass will be content with small amounts of water on a regular basis. Most of their roots are in the top several inches of the soil. And a good-looking lawn will have billions of healthy, greedy roots. Trees, shrubs and most other plants will have roots that go deeper into the soil. If the water doesnít penetrate deep enough to reach them, they continue to sit in dry soil. There are no reserves of soil moisture waiting to be tapped because of the lack of rain in the last three or four months. If there is grass growing over the root zones of these trees and shrubs, even less moisture will get through because the efficient grass roots will nab it. Your trees and shrubs and many other plants need less frequent watering with moisture being allowed to penetrate the soil to a much deeper level. Take your trusty shovel and dig near the plants and see how far the water has soaked. Lawn irrigation systems are not designed to water those guys with deeper roots. Watering should be determined by the soil moisture and to the depth of where it has soaked. Donít time it with your watch.